We propose to persue the following projects: (1) Sequence analysis of polio virus proteins VPg and VP4; (2) Sequence analysis of the poliovirus type 1, genome; (3) an investigation of the role VPg may play in viral replication; (4) mapping of VPg in the polio genome. This, we hope, will elucidate some key problems in the molecular biology of picornaviruses, namely, the nature of the ribosome attachment site and the mechanism of replication of viral RNA.